Call admission control (CAC) is employed in wireless networks to make decisions on whether or not to admit a new call. Such decisions are necessary in order to make sure there is capacity for the new call, and to determine if admitting the new call will have a negative effect on existing calls.
In existing call admission control mechanisms, the assumption is typically made that the capacity that limits call admission is that of the access links, and that so long as there is capacity on the access link, the backhaul network will have sufficient capacity.